Stable non-aqueous single phase viscous vehicles and formulations utilizing such vehicles

ABSTRACT

This invention relates to stable non-aqueous single phase viscous vehicles and to formulations utilizing such vehicles. The formulations comprise at least one beneficial agent uniformly suspended in the vehicle. The formulation is capable of being stored at temperatures ranging from cold to body temperature for long periods of time. The formulations are capable of being uniformly delivered from drug delivery systems at an exit shear rate of between about 1 to 1×10 −7  reciprocal second.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.13/043,288, filed 8 Mar. 2011, now pending, which is a Continuation ofU.S. patent application Ser. No. 12/075,435, filed 11 Mar. 2008, nowU.S. Pat. No. 7,919,109, which is a Continuation of U.S. patentapplication Ser. No. 09/627,531, filed 28 Jul. 2000, now abandoned,which is a Continuation-in-Part of U.S. patent application Ser. No.09/497,422, filed 3 Feb. 2000, now U.S. Pat. No. 7,258,869, which claimsthe benefit of U.S. Provisional Application Ser. No. 60/119,170, filed 8Feb. 1999, now expired, all of which applications are hereinincorporated by reference in their entireties in the presentapplication.

FIELD OF THE INVENTION

This invention relates to stable non-aqueous single phase biocompatibleviscous vehicles capable of suspending beneficial agents and uniformlydispensing said agents at low flow rates and more particularly to stableuniformly mixed formulations of beneficial agents in stable non-aqueoussingle phase biocompatible viscous vehicles.

REFERENCES

The following references are referred to by numbers in brackets ([ ]) atthe relevant portion of the specification.

-   1. Wang, et al., J. Parenteral Sci. Tech, 42: S4-S26 (1988).-   2. Desai, et al., J. Am. Chem. Soc., 116: 9420-9422 (1994).-   3. Chang, et al., Pharm. Tech., 80-84 (January 1996).-   4. Manning, et al., Pharm. Res., 6: 903-918 (1989).-   5. Hageman, Drug Dev. Ind. Pharm, 14: 2047-2070 (1988).-   6. Bell, et al., Biopolymers, 35: 201-209 (1995).-   7. Zhang, et al., Pharm. Res. 12: 1447-1452 (1995).-   8. PCT published application 98/00158-   9. PCT published application 98/16250-   10. Knepp, et al., Pharm. Res. 15 (7) 1090-1095 (1998).-   11. PCT published application 98/00157-   12. PCT published application 98/00152-   13. U.S. Pat. No. 5,540,912-   17. Yu, et al., J. Pharm. Sci., 85: 396-401 (1996).-   18. Mitchell, U.S. Pat. No. 5,411,951 (1995).-   19. Brooks, et al., U.S. Pat. No. 5,352,662 (1994)-   20. Geller, L., U.S. Pat. No. 3,869,549 (1975).-   21. Larsen, et al., PCT Publication No. WO95/34285 (1995).-   22. Knepp, et al., J. Pharm. Sci. Tech, 50: 163-171 (1996).-   23. U.S. Pat. No. 5,614,221-   24. U.S. Pat. No. 4,594,108-   25. U.S. Pat. No. 5,300,302-   26. U.S. Pat. No. 4,588,614-   27. U.S. Pat. No. 4,310,516-   28. U.S. Pat. No. 5,635,213-   29. EP 379,147

BACKGROUND OF THE INVENTION

Peptides, polypeptides, proteins and other proteinaceous substances(e.g., viruses, antibodies) collectively referred to herein as proteins,have great utility as pharmaceuticals in the prevention, treatment anddiagnosis of disease. Proteins are naturally active in aqueousenvironments, thus the preferred formulations of proteins have been inaqueous solutions. However, proteins are only marginally stable inaqueous solutions. Thus, protein pharmaceuticals often have shortshelf-lives under ambient conditions or require refrigeration. Further,many proteins have only limited solubility in aqueous solutions. Evenwhen they are soluble at high concentrations, they are prone toaggregation and precipitation.

Because proteins can easily degrade, the standard method for deliveringsuch compounds has been daily injections. Proteins can degrade via anumber of mechanisms, including deamidations of asparagine andglutamine; oxidation of methionine and, to a lesser degree, tryptophan,tyrosine and histidine; hydrolysis of peptide bonds; disulfideinterchange; and racemization of chiral amino acid residues [1-7]. Wateris a reactant in nearly all of these degradation pathways. Further,water acts as a plasticizer, which facilitates unfolding andirreversible aggregation of proteins. Since water is a participant inalmost all protein degradation pathways, reduction of aqueous proteinsolution to a dry powder provides an alternative formulation methodologyto enhance the stability of protein pharmaceuticals.

One approach to stabilizing proteins is to dry them using varioustechniques, including freeze-drying, spray-drying, lyophilization, anddesiccation. Dried proteins are stored as dry powders until their use isrequired.

A serious drawback to drying of proteins is that often one would like touse proteins in some sort of flowable form. Parenteral injection and theuse of drug delivery devices for sustained delivery of drug are twoexamples of the applications where one would like to use proteins in aflowable form. For injection, dried proteins must be reconstituted,adding additional steps which are time-consuming and where contaminationmay occur, and exposing the protein to potentially destabilizingconditions [7]. For drug delivery devices the protein formulations mustbe stable for extended periods of time at body temperature and maintaintheir flowability for the expected life of the device.

Solution formulations of proteins/peptides in non-aqueous polar aproticsolvents such as DMSO and DMF have been shown to be stable at elevatedtemperatures for long periods of time [8]. However, such solvent basedformulations will not be useable for all proteins since many proteinshave low solubility in these solvents. The lower the solubility of theprotein in the formulation, the more solvent would have to be used fordelivery of a specific amount of protein. Low concentration solutionsmay be useful for injections, but may not be useful for long termdelivery at low flow rates.

Proteins have been formulated for delivery using perfluorodecalin [9,10], methoxyflurane [9], high concentrations in water [11], polyethyleneglycol [12], PLGA [13, 14], ethylenevinylacetate/polyvinylpyrridonemixtures [15], PEG400/povidone [16]. However, these formulations werenot shown to retain a uniform suspension of protein in viscous vehicleover long periods of time.

Many biologically active compounds degrade over time in aqueoussolution. Carriers in which proteins do not dissolve but rather aresuspended, can often offer improved chemical stability. Furthermore, itcan be beneficial to suspend the beneficial agent in a carrier when theagent exhibits low solubility in the desired vehicle. However,suspensions can have poor physical stability due to settling andagglomeration of the suspended beneficial agent. The problems withnon-aqueous carriers tend to be exacerbated as the concentration of theactive compound is increased.

Dispersing powdered proteins or peptides in lipid vehicles to yieldparenteral sustained release formulations has been investigated [17-21].The vehicles used were either various vegetable (sesame, soy, peanut,etc.) or synthetic oils (e.g., Miglyol) gelled with aluminum fatty acidesters such as aluminum stearates (mono-, di- or tri-), or with apolyglycerol ester. Although theoretically these vehicles might precludesolution denaturation and protect the drug from aqueous chemicaldegradation, the vehicles themselves are unstable at highertemperatures. The storage of liquid vegetable oils at body temperaturesresults in the formation of reactive species such as free fatty acidsand peroxides (a process which is accelerated by the presence of tracesof various metal ions such as copper or iron which can leach from someimplantable devices). These peroxides not only adversely affect proteinstability [22] but would be toxic when delivered directly to forexample, the central nervous system of a human or animal.

The sustained delivery of drugs has many advantages. Use of implantabledevices assures patient compliance, since the delivery device istamper-proof. With one insertion of a device, rather than dailyinjections, there is reduced site irritation, fewer occupational hazardsfor practitioners improved cost effectiveness through decreased costs ofequipment for repeated injections, reduced hazards of waste disposal,and enhanced efficacy through controlled release as compared with depotinjection. The use of implantable devices for sustained delivery of awide variety of drugs or other beneficial agents is well known in theart. Typical devices are described, for example, in U.S. Pat. Nos.5,034,229; 5,057,318; 5,110,596; and 5,782,396. The disclosure of eachof these patents is incorporated herein by reference.

For drug delivering implants, dosing durations of up to one year are notunusual. Beneficial agents which have low therapeutic delivery rates areprime candidates for use in implants. When the device is implanted orstored, settling of the beneficial agent in a liquid formulation canoccur. This heterogeneity can adversely affect the concentration of thebeneficial agent dispensed. Compounding this problem is the size of theimplanted beneficial agent reservoir. Implant reservoirs are generallyon the order of 25-250 μl, but can be up to 25 ml.

Viscous formulations have been prepared using two separate components tobe mixed with drug at use [23], thickening agents added to aqueouscompositions [24], gelling agents added to aqueous drug solutions, [25],porous textile sheet material [26], thickening agents with oleaginousmaterial [27], viscous aqueous carrier for limited solubility drug [28],and extrudable elastic gels [29]. However, these formulations are mixedat use, contain aqueous components, use sheet matrices, or are deliveredtopically, orally, or intraduodenally.

Stability of formulations can be enhanced by freeze-drying, lyophilizingor spray-drying the active ingredient. The process of drying the activeingredient includes further advantages such as compounds which arerelatively unstable in aqueous solution can be processed and filled intodosage containers, dried without elevated temperatures, and then storedin the dry state in which there are relatively few stability problems.

Pharmaceutical formulations, particularly parenteral products, should besterilized after being sealed in the final container and within as shorta time as possible after the filling and sealing have been completed.(See, for example Remington, Pharmaceutical Sciences, 15^(th) ed.(1975)). Examples of sterilization techniques include thermal ordry-heat, aseptic, and ionized radiation. Combinations of thesesterilization procedures may also be used to produce a sterile product.

There is a need to be able to deliver protein compositions to the bodywhich are stable at body temperatures over extended periods of time toenable long term delivery of the protein. There is a need to be able todeliver concentrations of proteins that are efficacious. There is a needfor a novel non-aqueous formulation capable of homogeneously suspendingproteins and dispensing such agents at body temperatures and low flowrates over extended periods of time.

SUMMARY OF THE INVENTION

The present invention provides stable single phase non-aqueousbiocompatible viscous vehicles capable of forming uniform suspensionswith proteins. The components of the viscous vehicle comprise at leasttwo of polymer, surfactant, and solvent. The ratios of the componentswill vary depending on the molecular weight of the components and thedesired viscosity of the final vehicle. Presently preferred componentratios are: polymer, about 5% to about 60%; solvent, about 5% to about60%; and sufactant, about 5% to about 40%.

The present invention also provides stable formulations in whichbeneficial agents are uniformly suspended in stable single phasenon-aqueous biocompatible viscous vehicles. In particular, thebeneficial agents are formulated in the viscous vehicles atconcentrations of at least about 0.1%, depending upon the potency of thebeneficial agent. These stable formulations may be stored at thetemperature appropriate for the beneficial agent, ranging from cold, tobody temperature (about 37° C.) for long periods of time (1 month to 1year or more). In a preferred embodiment the formulation comprises about0.1 to 50% (w/w) of beneficial agent, depending on the potency of thebeneficial agent, the duration of treatment, and the rate of release forthe drug delivery system.

These formulations are especially useful in implantable delivery devicesfor long term delivery (e.g., 1 to 12 months or longer) of beneficialagent at body temperature, preferably about 37° C. Thus, the presentinvention also provides for the delivery of said proteins to the bodyover extended period of time to enable long term delivery of the proteinat low flow rates of about 0.3 to 100 μl/day, preferably about 0.3 to 4μl/day for about a 6 month delivery period and preferably 5 to 8 μl/dayfor about a 3 month delivery period.

In another aspect, the invention provides methods for preparing stablenon-aqueous biocompatible formulations of a beneficial agent in a singlephase viscous vehicle. Preferred formulations comprise about 0.1 to 50%(w/w) beneficial agent depending on the potency of the beneficial agent,the duration of treatment, and the rate of release from the deliverysystem.

In yet a further aspect, the invention provides methods for treating asubject suffering from a condition which may be alleviated byadministration of a beneficial agent, said methods comprisingadministering to said subject an effective amount of a stablenon-aqueous formulation comprising at least one beneficial agentuniformly suspended in a single phase viscous vehicle.

A further aspect of the invention is that non-aqueous single phaseviscous vehicles containing beneficial agents are chemically andphysically stable over a broad temperature range for long periods oftime. The beneficial agents in the viscous vehicles are also chemicallyand physically stable over a broad temperature range for long periods oftime. Thus, these formulations are advantageous in that they may beshipped and stored at temperatures below, at, or above room temperaturefor long period of time. They are also suitable for use in implantabledelivery devices in which the formulation must be stable at bodytemperature for extended periods of time.

The formulations of the present invention also remain stable whendelivered from implantable drug delivery systems. The beneficial agentshave been shown to exhibit zero order release rates when delivered fromimplantable drug delivery systems at very low flow rates over extendedperiods of time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the stability of hGH formulations of the present inventionas determined at 37° C. by reverse phase HPLC.

FIG. 2 shows the stability of hGH formulations of the present inventionas determined at 37° C. by size exclusion chromatography.

FIG. 3 shows the average release rate (μl/day) of 10% (w/w) spray-driedlysozyme in formulations of the present invention.

FIG. 4 shows the average release rate (μl/day) of 10% (w/w) spray-driedhGH in a glycerol monolaurate/lauryl lactate/polyvinylpyrrolidonevehicle.

FIG. 5 shows the average release rate (μg/day) of 10% lysozyme in alauryl alcohol/polyvinylpyrrolidone vehicle.

FIG. 6 shows the average release rate ((μg/day) of 25% lysozyme in aglycerol monolaurate/lauryl lactate/polyvinylpyrrolidone vehicle.

FIG. 7 shows the average release rate ((μg/day) of 33% lysozyme in aglycerol monolaurate/lauryl lactate/polyvinylpyrrolidone vehicle.

FIG. 8 shows the average release rate ((μg/day) of 45% lysozyme in aglycerol monolaurate/lauryl lactate/polyvinylpyrrolidone vehicle.

FIG. 9 and FIG. 10 are partial cross-sectional views of two embodimentsof the delivery device of the invention.

FIG. 11 is an enlarged cross-sectional view of the back-diffusionregulating outlet of FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is drawn to the unexpected discovery thatuniformly suspending beneficial agents in non-aqueous single phasebiocompatible viscous vehicles results in stable formulations which canbe delivered at body temperature over an extended period of time at lowflow rates. Previously known formulations of beneficial agents which arebuffered aqueous or non-aqueous solutions-which may or may not containexcipients do not provide formulations which can be uniformly dispensedat body temperatures at low flow rates over an extended period of timewithout exhibiting unacceptable amounts of aggregation or degradation ofthe formulation. The presently claimed formulations stabilize beneficialagents and can be stored at the temperature appropriate for thebeneficial agent. The temperatures can range from cold (not exceeding 8°C.) to body temperature (about 37° C.) for long periods of time. Theseformulations are especially useful in implantable delivery devices forlong term delivery (e.g., 1 to 12 months or longer) of drug at low flowrates and at body temperature, preferably about 37° C.

Standard beneficial agent formulations consist of dilute aqueous ornon-aqueous solutions or suspensions. Drug stability is usually achievedby varying one or more of the following: pH, buffer type, ionicstrength, excipients (EDTA, ascorbic acid, etc.) For these formulations,degradation pathways requiring water (hydrolysis, deamidation,racemization) cannot be fully stabilized. In the present invention,beneficial agents formulated in non-aqueous biocompatible single phaseviscous vehicles containing for example, polyvinylpyrrolidone, vinylacetate, and/or polyoxyethylenepolyoxypropylene block copolymers wereshown to be chemically and physically stable. The viscosity of theformulation will depend upon a number of criteria, including thebeneficial agent potency and concentration, and the process by which theformulation is prepared. The viscosity of the formulation can be chosenso that the desired amount of beneficial agent is delivered over thedesired period of time.

The invention also consists of non-aqueous single phase biocompatibleviscous vehicles capable of uniformly suspending beneficial agents andformulations containing at least one beneficial agent uniformlysuspended in said viscous vehicle. The invention also consists offormulations containing at least one beneficial agent uniformlysuspended in a non-aqueous single phase biocompatible viscous vehicle,which formulations are stable for an extended period of time at bodytemperatures, and capable of delivering said beneficial agents uniformlyallow flow rates. The discovery consists of the realization that stablenon-aqueous viscous vehicles improve the stability of beneficial agentsin a wide range of formulation conditions including concentration,elevated temperatures and duration of stable formulation, thus makingpossible the delivery of beneficial agents in long term implantabledevices that would not otherwise be feasible.

DEFINITIONS

As used herein, the following terms have the following meanings:

The term “chemical stability” means that an acceptable percentage ofdegradation products produced by chemical pathways such as oxidation,deamidation, or hydrolysis is formed. In particular, a formulation isconsidered chemically stable if no more than about 35% breakdownproducts are formed after 2 months at 37° C.

The term “physical stability” means that an acceptable percentage ofaggregates (e.g., dimers, trimers and larger forms) are formed by thebeneficial agent. For the formulation (viscous vehicle and beneficialagent) to this term means that the formulation retains stability,flowability, and the ability to uniformly dispense the beneficial agent.In particular, a formulation is considered physically stable if no morethan about 15% aggregates are formed after two months at 37° C.

The term “stable formulation” means that at least about 65% chemicallyand physically stable beneficial agent remains after two months at 37°C. (or equivalent conditions at an elevated temperature). Particularlypreferred formulations are those which retain at least about 80%chemically and physically stable beneficial agent under theseconditions. Especially preferred stable formulations are those which donot exhibit degradation after sterilizing irradiation (e.g., gamma, betaor electron beam).

The term “beneficial agent” means peptides, proteins, nucleotides,hormones, viruses, antibodies, etc. that comprise polymers of amino acidor nucleic acid residues. These beneficial agents are generallydegradable in water and generally stable as a dry powder at elevatedtemperatures. Synthetically produced, naturally derived or recombinantlyproduced moieties are included in this term. The term also includeslipoproteins and post translationally modified forms, e.g., glycosylatedproteins. Analogs, derivatives, agonists, antagonists andpharmaceutically acceptable salts of any of these are included in thisterm. The term also includes proteins and/or protein substances whichhave D-amino acids, modified, derivatized or non-naturally occurringamino acids in the D- or L-configuration and/or peptomimetic units aspart of their structure. The term protein will be used in the presentinvention. The term also means that the beneficial agent is present inthe solid state, e.g., powder or crystalline.

The term “excipient” means a more or less inert substance in aformulation that is added as a diluent or vehicle or to give form orconsistency. Excipients are distinguished from solvents such as ETOH,which are used to dissolve drugs in formulations. Excipients includenon-ionic surfactants such as polysorbates, which are used to solubilizedrugs in formulations; preservatives such as benzyl alcohols or methylor propyl parabens, which are used to prevent or inhibit microbialgrowth; chelating agents; flavoring agents; and other pharmaceuticallyacceptable formulation aides.

The term “viscous vehicle” means a vehicle with a viscosity in the rangeof about 1,000 to 10,000,000 poise. The term includes Newtonian andnon-Newtonian materials. Preferred are vehicles with a viscosity ofabout 10,000 to 250,000 poise. The formulations of this invention canuniformly is expel beneficial agents suspended in the viscous vehiclefrom implantable drug delivery devices. The formulations exhibit a shearrate at the exit of said devices of 1 to 1×10⁻⁷ reciprocal second,preferably an exit shear rate of 1×10⁻² to 1×10⁻⁵ reciprocal second.

The term “single phase” means a solid, semi-solid, or liquid homogeneoussystem that is both physically and chemically uniform throughout asdetermined by differential scanning calorimetry (DSC). The DSC scanshould show one peak indicative of a single phase.

The term “biocompatible” means a property or characteristic of a viscousvehicle to disintegrate or break down, over a prolonged period of time,in response to the biological environment in the patient, by one or morephysical or chemical degradative processes, for example by enzymaticaction, oxidation or reduction, hydrolysis (proteolysis), displacement,e.g. ion exchange, or dissolution by solubilization, emulsion or micelleformation, and which material is then absorbed by the body andsurrounding tissue, or otherwise dissipated thereby.

The term “polymer” includes polyesters such as PLA (polylactic acid)[having an inherent viscosity in the range of about 0.5 to 2.0 i.v.] andPLGA (polylacticpolyglycolic acid) [having an inherent viscosity in therange of about 0.5 to 2.0 i.v.], pyrrolidones such aspolyvinylpyrrolidone (having a molecular weight range of about 2,000 to1,000,000), esters or ethers of unsaturated alcohols such as vinylacetate, and polyoxyethylenepolyoxypropylene block copolymers(exhibiting a high viscosity at 37° C.) such as Pluronic 105. Currentlypreferred polymer is polyvinylpyrrolidone.

The term “solvent” includes carboxylic acid-esters such as lauryllactate, polyhydric alcohols such as glycerin, polymers of polyhydricalcohols such as polyethylene glycol (having a molecular weight of about200 to 600), fatty acids such as oleic acid and octanoic acid, oils suchas castor oil, propylene carbonate, lauryl alcohol, or esters ofpolyhydric alcohols such as triacetin acetate. Currently preferred islauryl lactate.

The term “surfactant” includes esters of polyhydric alcohols such asglycerol monolaurate, ethoxylated castor oil, polysorbates (for examplePolysorbate 80), esters or ethers of saturated alcohols such as myristyllactate (Ceraphyl 50), and polyoxyethylenepolyoxypropylene blockcopolymers such as Pluronic (for example, F68). Currently preferred aregylcerol monolaurate aria polysorbates.

The term “antioxidant” means a pharmaceutically acceptable aid forstablization of the beneficial agent against degradation such asoxidation. Antioxidants include, but are not limited to tocopherol(vitamin E), ascorbic acid, ascorbyl palmitate, butylatedhydroxyanisole, butylated hydroxytoluene, and propyl gallate. Apreferred antioxidant depends on solubility and the efficiency of theantioxidant for protecting against degradation or chemical change of thebeneficial agent in the preferred vehicle. Currently preferred isascorbyl palmitate.

Preparation of Formulations

The present invention is drawn to stable non-aqueous single phasebiocompatible viscous vehicles capable of suspending beneficial agentsand uniformly dispensing said beneficial agents at body temperatures atlow flow rates over an extended period of time. The present invention isalso directed to formulations containing beneficial agents uniformlysuspended in said single phase biocompatible viscous vehicles which arestable for prolonged periods of time at body temperatures.

Examples of beneficial agents that may be formulated using the presentinvention include those peptides or proteins that have biologicalactivity or that may be used to treat a disease or other pathologicalcondition. They include, but are not limited to, adrenocorticotropichormone, angiotensin I and II, atrial natriuretic peptide, bombesin,bradykinin, calcitonin, cerebellin, dynorphin N, alpha and betaendorphin, endothelin, enkephalin, epidermal growth factor, fertirelin,follicular gonadotropin releasing peptide, galanin, glucagon,glucagon-like peptide-1 (GLP-1), gonadorelin, gonadotropin, goserelin,growth hormone releasing peptide, histrelin, human growth hormone,insulin, interferons, leuprolide, LHRH, motilin, nafarerlin,neurotensin, oxytocin, relaxin, somatostatin, substance P, tumornecrosis factor, triptorelin, vasopressin, growth hormone, nerve growthfactor, blood clotting factors, ribozymes, and antisenseoligonucleotides. Analogs, derivatives, antagonists agonists andpharmaceutically acceptable salts of the above may also be used.

The beneficial agents useful in the formulations and methods of thepresent invention can be used in the form of a salt, preferably apharmaceutically acceptable salt. Useful salts are known to those ofskill in the art and include salts with inorganic acids, organic acids,inorganic bases, or organic bases.

Beneficial agents that are not readily soluble in non-aqueous solventsare preferred for use in the present invention. One of skill in the artcan easily determine which compounds will be useful on the basis oftheir solubility. The amount of beneficial agent may vary depending onthe potency of the compound, the condition to be treated, the solubilityof the compound, the expected dose and the duration of administration.(See, for example, Gilman, et. al, The Pharmacological Basis ofTherapeutics, 7^(th) ed, (1990) and Remington, Pharmacological Sciences,18^(th) ed. (1990), the disclosures of which are incorporated herein byreference.)

It has been unexpectedly found that using a stable non-aqueous singlephase biocompatible viscous vehicle increases the stability of thebeneficial agent. For example, as seen in FIGS. 1 and 2, human growthhormone (hGH) was found to be stable at 37° C. over 12 weeks informulations of polyvinylpyrrolidone/PEG; Pluronic; and glycerolmonolaurate/lauryl lactate/polyvinylpyrrolidone. FIG. 1 shows stabilityresults using reverse phase HPLC. FIG. 2 shows stability results usingsize exclusion chromatography.

Generally, stable non-aqueous single phase biocompatible viscousvehicles may be prepared by combining the dry (low moisture content)ingredients in a dry box or under other dry conditions and blending themat elevated temperature, preferably about 40 to about 70° C., to allowthem to liquify. The liquid vehicle is allowed to cool to roomtemperature. Differential scanning calorimetry was used to verify thatthe vehicle was single phase. The final moisture content of the viscousvehicle was <2%.

Generally, the stable formulations of the present invention may beprepared by combining the vehicle and beneficial agent under dryconditions and blending them under vacuum at elevated temperature,preferably about 40 to about 70° C., to disperse the beneficial agentuniformly throughout the vehicle. The formulation is allowed to cool toroom temperature.

It has been found that drying the beneficial agent prior to formulationenhances the stability of the formulation.

It has also been found that adding antioxidants, such as tocopherol,ascorbic acid, ascorbyl palmitate, butylated hydroxyanisole, butylatedhydroxytoluene, and propyl gallate reduces the formation of degradationproducts (e.g., unstable chemical intermediates) during sterilization.

Methodology

We have found that stable non-aqueous beneficial agent formulationsutilizing viscous vehicles may be prepared by combining the ingredientsfor the viscous vehicle under dry conditions and blending them atelevated temperature to allow them to liquify and form a single phase.Once a single phase viscous vehicle is formed, the vehicle is allowed tocool to room temperature. Beneficial agent is added with mixing atelevated temperature under vacuum to uniformly disperse it in theviscous vehicle.

We have tested these beneficial agent formulations, for exampleformulations of hGH, for stability by subjecting them to acceleratedaging tests. Results show that these formulations remained stable overextended periods of time.

We have tested beneficial agent formulations, for example human growthhormone and lysozyme, for stability by suspending them in a variety ofnon-aqueous single phase viscous vehicles prepared according to thepresent invention, then subjecting them to accelerated aging at elevatedtemperatures. The stability of the formulations was measured. Results ofthese studies demonstrate that these formulations were stable atconditions that approximate or exceed storage for one year at 37° C.

We have also tested beneficial agent formulations prepared as describedherein for stability after 2.5 megarads gamma irradiation. Results showthat those formulations remained chemically and physically stable aftersuch irradiation.

Methods

The following methods were used to perform the studios in the Examplesthat follow.

1. Preparing Protein Powders

-   -   Human Growth Hormone (obtained for example, from BresaGen        Limited, Adelaide, Australia)

The active agent was reconstituted in deionized water. The solutioncontaining the active agent was buffer exchanged using an Amicon Diaflo®Ultrafiltration membrane (molecular weight cut-off 10,000).

The diafiltrated active agent solution was spray dried using a Yamatomini-spray dryer. Powder was collected in a collection vessel through acyclone trap. All handling of the spray dried powder took place in a drybox evacuated with nitrogen. The generated powder was analyzed forparticle size and distribution, moisture content, protein content andstability by size exclusion and reverse-phase chromatography.

It is known that the conformation of some proteins can be stabilized bythe addition of a sugar (such as sucrose or mannitol) or a polyol (suchas ethylene glycol, glycerol, glucose, and dextran.)

2. Preparation of Viscous Vehicles

We have found that stable single phase biocompatible viscous vehiclesmay be prepared by combining the ingredients and blending them atelevated temperatures to allow them to liquify and form a single phase.A differential scanning calorimetry scan showed one peak, indicative ofa single phase.

The mixing was completed under vacuum to remove trapped air bubblesproduced from the powders. The mixer was a dual helix blade mixer(D.I.T.) which runs at a speed around 40 rpm. Higher speeds can be usedbut are not required.

If a three component viscous vehicle is prepared, the solvent portion ofthe vehicle was added to the heated bowl of the mixer first, followed bythe surfactant. The polymer was added last, and the ingredients weremixed until a solution (single phase) resulted. Vacuum was appliedduring mixing to remove air bubbles. The solution was dispensed from thebowl while at elevated temperature, and allowed to cool to roomtemperature. On cooling the vehicle exhibited increased viscosity. Twoand single component gels were made using the same process.

3. Preparation of Beneficial Agent Formulations

To prepare the formulation, the single phase viscous vehicle was heatedand then blended under vacuum with a weighed amount of beneficial agent.The beneficial agent and the single phase viscous vehicle were blendedin the same manner as the vehicle was prepared, using a dual helix blademixer (or other similar mixer). Mixing speed was between 40 and 120 rpmfor approximately 15 minutes or until a uniform dispersion was attained.The resulting mixture was removed from the mixer, sealed in a drycontainer, and allowed to cool to room temperature.

4. Preparation of Reservoirs

FIG. 9 shows one embodiment of the device according to the invention. InFIG. 9 a fluid-imbibing system 10 is shown that comprises an impermeablereservoir 12. The reservoir 12 is divided into two chambers by a piston16. The first chamber 18 is adapted to contain an active agent and thesecond chamber 20 is adapted to contain a fluid-imbibing agent. Aback-diffusion regulating outlet 22 is inserted into the open end of thefirst compartment 18 and a water-swellable semipermeable plug 24 isinserted into the open end of the second chamber 20. In FIG. 9, theback-diffusion regulating outlet 22 is shown as a male threaded memberin a mating relationship with the smooth interior surface of thereservoir 12 thereby forming therebetween helical flow path 34. Thepitch (x), the amplitude (y), and the cross-sectional area and shape ofthe helical path 34 formed between the mating surfaces of theback-diffusion regulating outlet 22 and the reservoir 12 as shown inFIG. 11 are factors that affect both the efficiency of path 34preventing back-diffusion of external fluid into the formulation inchamber 18 and the back pressure in the device. The geometry of outlet22 prevents water diffusion into the reservoir. In general, it isdesired that these characteristics be selected so that the length of thehelical flow path 34 and the velocity of flow of active agenttherethrough is sufficient to prevent back-diffusion of external fluidthrough the flow path 34 without significantly increasing the backpressure, so that, following start-up, the release rate of the activeagent is governed by the osmotic pumping rate.

FIG. 10 is a second embodiment of the device of the invention with areservoir 12, piston 16 and plug 26. In this embodiment, the flow path36 is formed between a threaded back-diffusion regulating outlet 40 andthreads 38 formed on the interior surface of the reservoir 12. Theamplitudes of the threaded portions of the back-diffusion regulatingoutlet 40 and reservoir 12 are different so that a flow path 36 isformed between the reservoir 12 and the back-diffusion regulating outlet40. The water-swellable semipermeable plugs 24 and 26 shown in FIGS. 9and 10 respectively are inserted into the reservoir such that thereservoir wall concentrically surrounds and protects the plug.

In FIG. 9, the top portion 50 of the plug 24 is exposed to theenvironment of use and may form a flanged end cap portion 56 overlayingthe end of reservoir 12. The semipermeable plug 24 is resilientlyengaged with the interior surface of the reservoir 12 and in FIG. 9 isshown to have ridges 60 that serve to frictionally engage thesemipermeable plug 24 with the interior of reservoir 12. In addition,the ridges 60 serve to produce redundant circumferential seals thatfunction before the semipermeable plug 24 expands due to hydration. Theclearance between ridges 60 and the interior surface of the reservoir 12prevents hydration swelling from exerting stresses on the reservoir 12that can result in tensile failure of the reservoir 12 or compression orshear failure of the plug 24.

FIG. 10 shows a second embodiment of the semipermeable plug 26 where theplug is injection molded into the top portion of the reservoir and wherethe top of the semipermeable plug 26 is flush with the top 62 of thereservoir 12. In this embodiment, the diameter of the plug issubstantially less than the diameter of the reservoir 12. In bothembodiments the plugs 24 and 26 will swell upon exposure to the fluid inbody cavity forming an even tighter seal with the reservoir 12.

An example of assembly of a delivery device is as follows. The pistonand inner diameter of the reservoir are lightly lubricated with siliconmedical fluid. The piston 16 is inserted into the open end of chamber20. Two osmotic engine tablets (40 mg each) are then inserted on top ofpiston 16. After insertion, the osmotic engine is flush with the end ofthe reservoir. The membrane plug 24 is inserted by lining up the plugwith the reservoir and pushing gently until the plug is fully engaged inthe reservoir. Active agent is loaded into a syringe which is then usedto fill chamber 18 from its open end by injecting the material into theopen tube until the formulation is ˜3 mm from the end. The filledreservoir is centrifuged (outlet end “up”) to remove any air bubblesthat are trapped in the formulation during filling. The outlet 22 isscrewed into the open end of the reservoir until completely engaged. Asthe outlet is screwed in, excess formulation exits out of the orificeensuring a uniform fill.

The reservoirs of implantable drug delivery devices (as disclosed inU.S. patent application Ser. No. 08/595,761, filed 2 Feb. 1996 (whichwas converted by petition to U.S. Provisional Patent Application Ser.No. 60/122,056 on 21 Jan. 1997), incorporated herein by reference) werefilled with the appropriate hGH formulation. The formulation was filledinto titanium reservoirs with a polymer plug blocking each end. Thefilled reservoir was then sealed in a polyfoil bag and placed in astability testing oven.

It should be noted that the formulations in the reservoirs of thesedevices are completely isolated from the outside environment.

5. Reverse Phase-HPLC (RP-HPLC)

All stability samples of hGH were assayed for protein content andchemical stability by reverse phase chromatography (RP-HPLC). Analyseswere performed on a Hewlett Packard HP-1090 system with a refrigeratedautosampler (4° C.). The chromatographic conditions used are listedbelow.

TABLE 1 RP-HPLC Chromatographic Conditions Description Parameter ColumnJ. T. Baker-C18, 4.6 × 250 mm Flow Rate 1.0 mL/min Detection 214 nmMobile Phase A: 0.1% TFA in water B: 0.1% TFA in acetonitrile Gradienttime % A % B 0 65 35 5 50 50 45 35 65 50 30 70 55 65 35

An hGH reference standard solution was prepared and its protein contentcalculated from the absorbance measurement at 280 nm. Three dilutions ofthis solution, representing 80%, 100%, and 120% of the expectedconcentration of hGH in the samples were run in duplicate at thebeginning and the end of each run and used to calculate total proteincontent of the samples.

6 Size Exclusion Chromatography (SEC)

All stability samples of hGH were assayed for protein content and highmolecular weight degradation products by size exclusion chromatography.Analyses were performed on a Hewlett Packard HP-1090 system with arefrigerated autosampler (4° C.). The chromatographic conditions usedare listed below

TABLE 2 SEC Chromatographic Conditions Description Parameter ColumnTSK-2000SWXL Flow Rate 0.5 ml/min Detection 214 nm Mobile Phase 25 mMsodium phosphate, 100 mM sodium chloride, pH 7.0

A hGH reference standard solution was prepared and its protein contentcalculated from the absorbance measurement at 280 nm. Three dilutions ofthis solution, representing 80%, 100%, and 120% of the expectedconcentration of hGH in the samples were run in duplicate at thebeginning and the end of each run and used to calculate total proteincontent of the samples. The amount of high molecular weight degradationproducts was calculated by area normalization.

The following examples are offered to illustrate this invention and arenot meant to be construed in any way as limiting the scope of thisinvention.

EXAMPLE 1 Preparation of Non-Aqueous Single Phase Viscous Vehicles

The non-aqueous single phase viscous vehicles can be prepared as followsand shown in the below table

-   A. Glycerol monolaurate (Danisco Ingredients, New Century, Kans.)    (25 g) was dissolved in lauryl lactate (ISP Van Dyk Inc.,    Belleville, N.J.) (35 g) at 65° C. Polyvinylpyrrolidone C30 (BASF,    Mount Olive, N.J.) (40 g) was added and the mixture blended at about    40 rpm in a dual helix blade mixer (D.I.T.) until a single phase was    achieved. Trapped air bubbles were removed by applying vacuum to the    mixing chamber. The single phase vehicle was dispensed from the    mixer, and allowed to cool to room temperature.-   B. Glycerol monolaurate (Danisco Ingredients, New Century, Kans.)    (25 g) was dissolved in lauryl lactate (ISP Van Dyk Inc.,    Belleville, N.J.) (35 g) at 65° C. Polyvinylpyrrolidone C17 (BASF,    Mount Olive, N.J.) (40 g) was added and the mixture blended at about    40 rpm in a dual helix blade mixer (D.I.T.) until a single phase was    achieved. Trapped air bubbles were removed by applying vacuum to the    mixing chamber. The single phase vehicle was dispensed from the    mixer, and allowed to cool to room temperature.-   C. Polyvinylpyrrolidone C30.(BASF, Mount Olive, N.J.) (50 g) was    dissolved in polyethylene glycol 400 (Union Carbide) (50 g) at    approximately 65° C. until a single phase solution was formed. The    single phase vehicle was dispensed from the mixer, and allowed to    cool to room temperature.-   D. Polyvinylpyrrolidone C17 (BASF, Mount Olive; NJ) (50 g) was    dissolved in polyethylene glycol 400 (Union Carbide) (50 g) at    approximately 65° C. until a single phase solution was formed. The    single phase vehicle was dispensed from the mixer, and allowed to    cool to room temperature.-   E. Polyvinylpyrrolidone C17 (BASF, Mount Olive, N.J.) (50 g) was    dissolved in castor oil (Spectrum, Gardena, Calif.) (50 g) at    approximately 65° C. until a single phase solution was formed. The    single phase vehicle was dispensed from the mixer, and allowed to    cool to room temperature.-   F. Polyvinylpyrrolidone C17 (BASF, Mount Olive, N.J.) (50 g) was    dissolved in octanoic acid (Spectrum, Gardena, Calif.) at    approximately 65° C. until a single phase solution was formed. The    single phase vehicle was dispensed from the mixer, and allowed to    cool to room temperature.-   G. Polyvinylpyrrolidone C17 (BASF, Mount Olive, N.J.) (50 g) was    dissolved in oleic acid (Spectrum, Gardena, Calif.) at approximately    65° C. until a single phase solution was formed. The single phase    vehicle was dispensed from the mixer, and allowed to cool to room    temperature.-   H. Polyvinylpyrrolidone C17 (BASF, Mount Olive, N.J.) (35%) was    dissolved in glycerin (Baker, N.J.) (65%) at approximately 65° C.    until a single phase solution was formed. The single phase vehicle    was dispensed from the mixer, and allowed to cool to room    temperature.-   I. Cremophor EL (ethoxylated castor oil) (BASF, Mount Olive, N.J.)    (5%) Q was dissolved in castor oil (Spectrum, Gardena, Calif.)    (70%), and polyvinylpyrrolidone C17 (BASF, Mount Olive, N.J.) (25%)    was added and dissolved by mixing at approximately 40 rpm to form a    single phase vehicle. The single phase vehicle was dispensed from    the mixer, and allowed to cool to room temperature.-   J. Pluronic 105 (BASF, Mount Olive, N.J.) was heated to    approximately 65° C. with mixing until melted. The single phase    vehicle was dispensed from the mixer, and allowed to cool to room    temperature.-   K. Pluronic F68 (BASF, Sigma) 10% w/w and butylhydroxytoluene    (Spectrum) 1% w/w were dissolved in 49% w/w propylene carbonate    (Aldrich) by mixing under vacuum at 60° C. until the materials    dissolved. The vacuum was released, and the resulting liquid was    added to 40% w/w poly lactic acid [poly(D,L-lactide), Resomer R207,    Boehringer Ingelheim]. All components were mixed by hand at 60° C.    using a spatula until the poly lactic acid was dissolved to form a    single phase vehicle. The single phase vehicle was moved to a vacuum    chamber to remove remaining air bubbles and allowed to cool to room    temperature.-   L. Myristyl lactate (Ceraphyl 50, ISP Van Dyk) 20% w/w was dissolved    in 25% w/w lauryl alcohol (Sigma) under vacuum at 60° C. until the    material dissolved. The vacuum was released, and the resulting    liquid was added to a mixing bowl. 55% w/w Polyvinylpyrrolidone    (BASF, 17pf) was added on top and the contents of the bowl were    mixed at 40 rpm at 60° C. under vacuum until all components were    miscible and formed a single phase vehicle. Vacuum was applied until    air bubbles were removed from the single phase vehicle.

TABLE 3 Component Ratios Viscosity at Component Low Shear PolymerSurfactant Solvent Ratio Rate (Poise) PVP GML LL 53:5:42  25,000 PVP GMLLL 55:10:35 50,000 PVP GML LL 50:15:35  7,000 PVP — LA 60:40 PVPCeraphyl 50 LA 60:10:30 PVP — oleic acid 50:50 30,000 PVP — octanoicacid 55:45  7.000 PVP polysorbate 80 — 50:50 PVP — PEG 400 50:50 PVPcaster oil — 50:50 — Pluronic 105 — 100 1,000,000   PVP — glycerin 50:50 5,000 PLA F68 PC  30:10:60* PVP (C17) ML LA 50:25:25 PVP (C17)polysorbate 80 LL 55:40:5  Wherein: GML = glycerol monolaurate LL =lauryl lactate PVP = polyvinylpyrrolidine C30 LA = lauryl alcohol PEG =polyethyleneglycol 400 F68 = poly(propylene oxide)/poly(ethylene oxide)block copolymer (a Member of the Pluronic family) PC = propylenecarbonate PLA = poly lactic acid ML = myristyl lactate *also contains 1%butylhydroxytoluene

EXAMPLE 2 Preparation of hGH

A. Preparation by Spray Drying

Lyophilized hGH (BresaGen Limited, Adelaide, Australia) wasreconstituted in 150 ml of deionized water. This stock solutioncontained 1050 mg of hGH. Buffer exchange was accomplished using anAmicon Diaflo® Ultrafiltration membrane (molecular weight cut-off10,000). The is ultrafiltration cell was connected to an auxilliaryreservoir containing 5 mM phosphate buffer (pH 7). The cell's fluidvolume, as well as the hGH concentration, remained constant asexcipients were replaced by phosphate buffer.

The diaflitrated protein solution (protein concentration in the solutionapproximately 2%) was spray dried using a Yamato mini-spray dryer.Settings on the spray dryer were as follows: aspiration pressureconstantly adjusted to 1.3 kgf/cm², inlet temperature 120° C., solutionflow rate 2.5 (approximately 3 ml/min). Powder was collected in acollection vessel through a cyclone trap. All handling of the spraydried powder took place in a dry box evacuated with nitrogen (% RH:1-4%). The water content of the suspending vehicles is shown in thebelow table.

TABLE 4 WATER CONTENT OF SUSPENDING VEHICLES Water Content of WaterContent of Vehicle Vehicle at T 0 in 12 wks. At 37° C. Vehicle % w/w %w/w Pluronic 105 0.25 0.4 GML/LL/PVP 1.5 1.3 PVP/PEG 2.0 2.0 Wherein:GML = glycerol monolaurate LL = lauryl lactate PVP =polyvinylpyrrolidine C30 PEG = polyethyleneglycol 400

EXAMPLE 3 Preparation of hGH Formulation

A portion of the single phase viscous vehicle was weighed (9 g) andheated to 60° C. hGH (BresaGen Limited, Adelaide, Australia) (1 g) wasadded to the vehicle and mixed for 15 minutes. The mixing was completedunder vacuum to remove air bubbles added from the powder.

Approximately 10 mg of the spray-dried hGH powder were weighed out(content of hGH in the powder was recalculated based on the determinedwater and salt content) and mixed with 100 μl of the vehicle at 55-65°C. (3 samples per each vehicle). Special care was taken while mixingpowder in the suspending vehicle to achieve maximum particle uniformdispersion in the vehicle. All steps were done in a dry box.

The resulting suspension was dissolved with 10 ml of release rate bufferand analyzed by size exclusion and reverse-phase chromatography. Spraydried hGH powder was used as a control.

TABLE 5 STABILITY OF hGH SUSPENSIONS AT 37° C. AS MEASURED BY SIZEEXCLUSION CHROMATOGRAPHY Spray-dried PVP/PEG 400 GML/LL/PVP Pluronic 105Time Powder −80° suspension suspension suspension Weeks C. % LS % LS %LS % LS 0 96 ± 1 88 ± 6 92 ± 2 87 ± 7 1 99 ± 8 81 ± 2 94 ± 3 93 ± 3 2 99± 3 83 ± 1 97 ± 1 94 ± 1 3 97 ± 1 84 ± 2 95 ± 2 95 ± 3 4 95 ± 2 82 ± 894 ± 4 93 ± 5 7 95 ± 4 76 ± 3 93 ± 4 88 ± 2 12 97 ± 4 79 ± 3 97 ± 1 95 ±6 Each data point represents the mean ± relative standard deviation ofthree individual samples taken from three separate vials.

TABLE 6 STABILITY OF hGH SUSPENSIONS at 37° C. AS MEASURED BY REVERSEPHASE CHROMATOGRAPHY spray-dried PVP/PEG 400 GML/LL/PVP Pluronic 105Time Powder −80° suspension suspension suspension Weeks C. % LS % LS %LS % LS 0 104 ± 1 99 ± 3 99 ± 2 89 ± 7 1 104 ± 8 78 ± 2 98 ± 3 96 ± 6 2104 ± 4 73 ± 3 95 ± 1 96 ± 1 3 104 ± 2 78 ± 4 97 ± 3 97 ± 4 4 100 ± 2 74 ± 10 93 ± 4 96 ± 4 7 108 ± 5 72 ± 4 96 ± 2 94 ± 2 9 102 ± 3 66 ± 392 ± 3 93 ± 2 12 101 ± 2 66 ± 1 89 ± 2 92 ± 5 Each data point representsthe mean ± relative standard deviation of three individual samples takenfrom three separate vials.

EXAMPLE 4 Preparation of Reservoirs Release Rate Profiles

Titanium reservoir systems of implantable drug delivery devices (asdisclosed in U.S. patent application Ser. No. 08/595,761, filed 2 Feb.1996 (which was converted by petition to U.S. Provisional PatentApplication Ser. No. 60/122,056 on 21 Jan. 1997), incorporated herein byreference) were each assembled with an osmotic engine, piston, and ratecontrolling membrane (i.e., a semipermeable plug). The reservoirs werefilled with the appropriate amount of viscous vehicle formulation andcapped with a flow plug (i.e., a back-diffusion regulating outlet). Thesystems were placed in a water bath at 37° C., and allowed to releaseformulation for an extended period of time. Released material wassampled twice per week. Assays for released material were completedusing reverse phase HPLC. The resulting concentrations of beneficialagent (i.e., active agent) for each system were converted to releasedamount per day. The beneficial agent was found to have a zero orderrelease from the implantable drug delivery device. As shown in FIGS. 3through 8.

EXAMPLE 5 Stability of hGH in Non-Aqueous Viscous Vehicle Formulations

Formulations of 10% w/w hGH in vehicle were prepared as described aboveand placed in vials. The formulations were subjected to acceleratedaging by storing them at elevated temperatures and times shown in thebelow table in a controlled temperature oven.

TABLE 7 % LS by % LS by Vehicle Time(hrs) Temperature SEC RP-HPLCPluronic 105 0 50° C. 98 ± 3 101 ± 3 Pluronic 105 1 50° C. 98 ± 3 101 ±4 Pluronic 105 2 50° C. 100 ± 1  102 ± 3 Pluronic 105 4 50° C. 101 ± 3 105 ± 3 GML/LL/PVP 0 65° C. 99 ± 3 101 ± 3 GML/LL/PVP 1 65° C. 93 ± 6 97 ± 6 GML/LL/PVP 2 65° C. 91 ± 5  95 ± 5 GML/LL/PVP 4 65° C. 95 ± 3 98 ± 3 Each data point represents the mean ± relative standarddeviation of three individual samples taken from three separate vials.

Results, presented in the following table, demonstrate that theseformulations were able to maintain the stability of the hGH in eachcase. In each case, at least 70% hGH was retained.

TABLE 8 RECOVERY OF hGH FROM NONAQUEOUS SUSPENSIONS % LS by Size-Vehicle % LS by RP-HPLC exclusion HPLC PVP/PEG 400 99 ± 3% 88 ± 6%GML/LL/PVP 99 ± 2% 92 ± 2% Pluronic 105 89 ± 7% 87 ± 7% Each data pointrepresents the mean ± relative standard deviation of three individualsamples taken from three separate vials. % LS or % label strength =(measured protein content + theoretical protein content) × 100%

EXAMPLE 6 A. Preparation by Spray Drying

GLP-1 (Polypeptide Laboratories, Wofenbuttel, Germany) was obtained asan acetate salt and was lyophilized. The lyophilized GLP-1 was dissolvedin purified water at 19.9 mg/ml and spray dried using a Yamatomini-spray dryer. The spray drying parameters were: 120° C. inlettemperature, 90° C. outlet temperature, solution flow rate 3.3-5.3ml/min. Powder was collected in a collection vessel through a cyclonetrap. All handling of the spray dried powder took place in a dry boxevacuated with nitrogen (% RH: 1-4%).

B. Preparation of GLP-1 Formulation

A portion of the single phase viscous vehicle was weighed and heated to60° C. GLP-1 (Polypeptide Laboratories, Wolfenbuttel, Germany) was added27% w/w to the vehicle and mixed for 15 minutes. The mixing wascompleted under vacuum to remove air bubbles.

The resulting suspension was dissolved in 10 ml of release rate bufferand analyzed by size exclusion and reverse-phase chromatography.

C. Analysis of GLP-1 Formulations

The reverse-phase HPLC method consisted of a C-8 5μ, 4.6×250 mmanalytical column (Higgins Analytical, Mountain View, Calif.) withdetection at 210 nm. A step gradient method from 25% B to 80% B at 1ml/min was as follows: 0-5 min at 25% 8, 5-30 min at 25-50% B, 30-35 minat 50-80% B. Mobile phase A was 0.1% TFA in water and mobile phase B was0.1% TFA in acetonitrile. The formulations were found to be stable for 6months.

The size exclusion chromatography method consisted of a Pharmacia FPLCHR 10/30 column at a flow rate of 0.5 ml/min. An isocratic method wasemployed, where the mobile phase was 100 mM ammonium phosphate, 200 mMsodium chloride, pH 2.0, and peptide was detected at 210 nm. Theformulations were found to be stable for 6 months.

D. Preparation of Reservoirs

Titanium reservoir systems of implantable drug delivery devices (asdisclosed in U.S. patent application Ser. No. 08/595,761, filed 2 Feb.1996 (which was converted by petition to U.S. Provisional patentapplication Ser. No. 60/122,056 on 21 Jan. 1997), incorporated herein byreference) were each assembled with an osmotic engine, piston, and ratecontrolling membrane (i.e., a semipermeable plug). The reservoirs werefilled with the appropriate amount of viscous vehicle formulation andcapped with a flow plug (i.e., a back-diffusion regulating outlet). Thesystems were placed in a water bath at 37° C., and allowed to releaseformulation for an extended period of time. Released material wassampled twice per week. Assays for released material were completedusing reverse phase HPLC. The resulting concentrations of beneficialagent (i.e., active agent) for each system were converted to releaseamount per day. The beneficial agent was found to have a zero orderrelease from the implantable drug delivery device.

Modification of the above-described modes of carrying out variousembodiments of this invention will be apparent to those of skill in theart following the teachings of this invention as set forth herein. Theexamples described above are not limiting, but are merely exemplary ofthis invention, the scope of which is defined by the following claims.

1. An implantable drug delivery device, comprising a reservoircontaining a beneficial agent formulation, the beneficial agentformulation comprising a stable non-aqueous single phase biocompatibleviscous vehicle, comprising a solvent component and a polymer component,wherein (i) the solvent component is a carboxylic acid ester or laurylalcohol, (ii) the polymer component is polyvinylpyrrolidone, and (iii)the viscous vehicle has a viscosity of about 10,000 to about 250,000poise at 37° C., and particles, comprising a beneficial agent, whereinthe particles are uniformly suspended in the vehicle; and saidimplantable drug delivery device further comprising an osmotic engine, apiston, and a rate controlling membrane.
 2. The device of claim 1,wherein the vehicle further comprises a surfactant component, whereinthe surfactant is glycerol monolaurate or a polysorbate.
 3. The deviceof claim 2, wherein the vehicle components are in the range of about 5%(w/w) to about 60% (w/w) for solvent, about 5% (w/w) to about 40% (w/w)for surfactant, and about 5% (w/w) to about 60% (w/w) for polymer. 4.The device of claim 1, wherein the formulation further comprises anantioxidant.
 5. The device of claim 4, wherein the antioxidant isselected from the group consisting of tocopherol, ascorbic acid,ascorbyl palmitate, butylated hydroxyanisole, butylated hydroxytoluene,and propyl gallate.
 6. The device of claim 1, wherein the formulationcan be delivered from the implantable drug delivery device such that theexit shear rate of the formulation is between about 1 and 1×10⁻⁷reciprocal second.
 7. The device of claim 1, wherein the formulation isstable at body temperature for extended periods of time.
 8. The deviceof claim 1, wherein the formulation comprises at least about 0.1% (w/w)beneficial agent.
 9. The device of claim 1, wherein the formulationcomprises at least about 10% (w/w) beneficial agent.
 10. The device ofclaim 1, wherein the formulation is stable at 65° C. for at least about2 months.
 11. The device of claim 1, wherein the formulation is stableat 37° C. for at least about 3 months.
 12. The device of claim 1,wherein the formulation is stable at 37° C. for at least about one year.13. The device of claim 1, wherein the beneficial agent is dried to alow moisture content prior to incorporation in the formulation.
 14. Thedevice of claim 1, wherein the particles are prepared by spray-drying.15. The device of claim 14, wherein the particles further comprise asugar.
 16. The device of claim 15, wherein the sugar is sucrose ormannitol.
 17. The device of claim 1, wherein the carboxylic acid esteris lauryl lactate.
 18. The device of claim 1, wherein during use theimplantable device provides a flow rate of the beneficial agentformulation of between 0.3 to 100 ul/day.
 19. The device of claim 1,wherein the vehicle comprises the solvent component and the polymercomponent in a ratio between 40:60 to 60:40.
 20. The device of claim 1,wherein the formulation further comprises a surfactant.
 21. The deviceof claim 1, wherein the solvent component is lauryl alcohol.
 22. Amethod of making the implantable drug delivery device of claim 1,comprising assembling the reservoir with the osmotic engine, the piston,and the rate controlling membrane, filling the reservoir with thebeneficial agent formulation, and capping the reservoir with a flowplug.